Do I need some kind of I.D.?

So, me and my friends wanna watch a movie this week and I was just
wondering some questions...
The thing is I haven't ever been to a theater.
My friends want me to pre-order the tickets online.
I went to order them and I decided to buy the Child tickets instead of
the Adult ones because they are cheaper to pay for. Do you need some
kind of I.D. if you pre-order your tickets to see if you are that age?
Also, my dad's paying for the tickets with his credit card so does he
need to be there to identify that the tickets are brought with his
credit card? Because when he ordered, he bought all Child tickets like
I had said. And they are for a PG movie...SO. PLEASE HELP ME (: